At times, it is desirable to deposit small particles, for example, microparticles and nanoparticles, onto a target material or otherwise expose the target material to these small particles. For example, in toxicology some types of toxicity investigations involve exposing cell cultures to particles under investigation. In the size realm of microparticles, the particles under investigation are typically impacted into a cell culture using a gas-jet impaction method. This method involves directing a jet of inert delivery gas containing the particles under investigation toward the cell culture. When the jet is close to the cell culture it is diverted by the culture in accordance with aerodynamic principles. However, because the particles are relatively massive, they cannot change direction as quickly as the gas molecules and continue toward the cell culture until they ultimately impact upon the culture. Of course, the gas-jet impaction method works only so long as the particles under investigation are massive enough so as to not divert around the culture along with the gas molecules.
In the size realm of nanoparticles, the gas-jet exposure method just described is not effective because the particles lack the mass needed for the method to work. When investigating the toxicity of nanoparticles, another type of exposure method is typically used. One such method involves dissolving the particles under investigation in a liquid solvent and exposing the cultured cells to the resulting solution. A shortcoming of this method is that it often does not model reality very well due to the dissolving step and presence of the solvent. This is so in situations wherein the type of cells under investigation, for example, lung cells, when in situ, are exposed directly to the particles and not a liquid solution. In these situations the particle-solution/cultured cell method does not accurately model the in-situ exposure of the actual cells.